1. Field of the Invention
The present invention concerns a system for the molding of tubular goods, comprising a mold having an inner mold part and an outer mold part which together define a mold cavity and an upwardly open annular pouring gate.
2. Description of the Related Art
When molding concrete pipes, for example, in such vertical molds, with the concrete being poured from the upper end of the mold, it is important that vibration is imparted to the poured concrete material to compact the concrete so that there will no voids in the cast concrete article. Today, the vibrations are imparted either by introducing poker vibrators down through the upper opening of the mold, or by imparting vibrations to either the inner mold part or to the outer side of the mold via the platform which carries the mold, for example, so that the vibrations spread via the mold into the concrete.
Particularly in connection with the so-called wet molding of concrete elements where the cast concrete element remains in the mold for a relatively long time, as the element is demolded only after the establishment of a bonding force between the concrete particles that is greater than the friction between the cast concrete element and the mold, it is important to keep down the mold costs, since the costs of such molds in mass production systems may be quite considerable because of the necessity of using several molds of the same type.
This problem is aggravated today by the increasing use of tubular goods of widely varying cross-sections, such as egg-shaped, four-sided and other cross-sections, which additionally increases the mold costs in a system of this type. In a system enabling switching between various forms of basic cross-sections, it has been attempted to keep down the mold equipment costs by reusing removable vibrators on the outer mold part of the various mold shapes and sizes. Although the relatively expensive vibrators are thus reduced considerably in number, it is clear that the actual mold equipment is made more expensive in any event, since the mold equipment has to be provided with mounting fittings or mating flanges to connect the individual mold with the vibrators.
Today, a system is known where the mold costs are minimized in that the system is provided with a plurality of poker vibrators, which are suspended over the mold equipment, and which may be lowered down into the mold during the molding process and be pulled up as the mold is filled. This known system is additionally adapted such that the individual vibrators may be displaced synchronously in a radial direction with respect to the mold, so that the system may be used for the molding of circular pipes of different diameters.